Height of raised bed/fencing to keep out squirrels?
I'm interested in building a raised bed like this one:
The raised bed is 20 inches tall, and the surrounding fencing is 12 inches tall. Do you think this combination of a high bed and minimal fencing will keep out the squirrels? I was playing with the idea of building the raised bed 24 inches tall, and using 18 inch tall fencing, but I'm not sure if even this is enough.
Thank you very much in advance!